1. Field of the Invention
The present invention relates to a novel compound which can be used for the preferential cleavage of a phosphodiester bond in a specific position of RNA. Thus, the invention provides a useful means for preparing, for instance, a deletion mutant. Thus, the invention broadly provides an effective means for treating RNA in the case of molecular biological experiments directed, for example, to the mass production of useful proteins, to the improvement of the properties of proteins, to studies of the relationship between the structure and the function of proteins, to the development of methods of eliminating toxic components in toxic RNA viruses, to the development of methods for treating diseases caused by toxic viruses, and to various studies concerning molecular biological science.
The invention relates also to oligomers to be used in said novel compound, and to starting materials for the syntheses of said oligomers.
A method for the preferential cleavage of a phosphodiester bond at a desired position of an RNA molecule will serve as a useful means for studying the structure and function of a functional RNA molecule. For instance, such a method may be employed in studies of the structure and stability of m-RNA which codes a useful protein or an enzyme protein, in relation to the translation rate. It is also possible to use such a method in research into the molecular structure and function of RNA virus genes which are harmful to animals and plants.
2. Description of the Prior Art
There are a number of known methods for the cleavage of a phosphodiester bond in an RNA molecule. One of these known methods comprises using a basespecific natural ribonuclease such as RNaseT.sub.1, RNaseU.sub.2 or the like. Another method comprises forming a double chain from an RNA molecule and a complementary DNA, and cleaving the RNA strand in the double chain by the use of RNaseH, i.e. ribonuclease H (H. Donis-Keller, Nucleic Acids Res., 7, 179, 1979). In the case of the former method, it is rather difficult to cleave the linkage only in the desired position of the molecule. In other words, in the case of the former method, the base-specific cleavage may occur at many sites of the molecule, so that the method is widely employed for the determination of the base sequence in an RNA molecule (H. Donis-Keller et al, Nucleic Acid Res., 4, 2527, 1977). In the case of the latter method, when a long DNA chain is employed, the cleavage will occur at various sites, and when a short DNA chain consisting of, for instance, 4 or 6 bases is employed, a preferential cleavage will be expected. However, if the DNA chain is short, such a short DNA chain will form a double chain at various positions without any substantial positional preference. Thus, according to these known methods, it is virtually impossible to preferentially cleave the phosphodiester bond in a desired position of an RNA molecule.
It is desired in the field of biological science to develop a novel method for the preferential cleavage of phosphodiester bond in a desired position of an RNA molecule without any limitation on the chain length and the base arrangement of the RNA. It is apparent that such a novel method will serve as a useful means in studies on the structure and the function of a functional RNA. Such studies are important, for instance, for the development of processes for the mass production of useful proteins, and of methods of improving the properties of proteins, and for the development of methods for the detoxication of harmful RNA viruses and methods for effectively treating diseases caused by such viruses.